The instant invention pertains to a superior process for making 2H-benzotriazole UV absorbers which are substituted by a perfluoroalkyl group, i.e. trifluoromethyl, usually at the 5-position of the benzo ring; and to a novel process for the preparation of the intermediate 2-(2-nitophenylazo)phenols.
Japanese TOKU-KAI-Hei 3-57690 generically discloses compounds where the benzo ring of the benzotriazole may be substituted by a host of groups including hydrogen, alkyl, alkoxy, aryloxy, halogen, substituted amino, cyano, nitro, acyl and trihalomethyl. The only specific benzotriazole compounds mentioned are those where the benzo ring is unsubstituted or is substituted at the 5-position by a chloro group. There is no evidence that the Japanese inventors made any trihalomethyl substituted benzotriazole.
German Patent Application 116,230 describes inter alia the preparation of 5-trifluoromethyl-2-(2-hydroxy-5-methylphenyl)-2H-benzotriazolyl-1-oxide. The only synthesis conditions disclosed for the entire group of compounds prepared show the diazotization of the appropriate o-nitroaniline with aqueous sodium nitrite and hydrochloric acid. The German workers offer no synthetic details or more importantly no yield information for the preparation of 5-trifluoromethyl-2-(2-hydroxy-5-methylphenyl)-2H-benzotriazolyl-1-oxide.
In British Patent Application 2,319,035 and U.S. Pat. No. 5,977,219, all benzotriazole compounds containing a trifluoromethyl moiety at the 5-position of the benzo ring are referenced to the synthetic procedure of Example 1. Issues to be considered with this synthetic procedure are (a) a 100% excess of the diazonium salt relative to phenol is used; (b) the monoazo prepared by this method is described as a paste (generally materials with the consistency of a paste are impure); the pure monoazo is a solid with a melting point of 101-105xc2x0 C.; (c) the yield of benzotriazole based on the phenol is 11% and is only 5.5% based on the CF3-substituted o-nitroaniline; (d) the diazotization preparation in Example 1 uses concentrated hydrochloric acid; (e) a paper in the J. Org. Chemistry, 1985, (50) 3612 indicates that the reaction of 4-trifluoromethyl-2-nitroaniline with hydrochloric acid can lead to the formation of 4-trifluoromethyl-2-chloroaniline. Such a reaction could at least partly account for the low yields seen with the use of concentrated hydrochloric acid in the diazotization step.
The following references describe one-pot processes for making azo compounds:
U.S. Pat. No. 2,418,416 describes a process for manufacturing lakes of azo compounds. The process involves dissolving the diazotizable amine and coupling component in an acidic, aqueous solution. The amine was diazotized by addition of the nitrosating reagent to the acidic, aqueous solution. After diazotization was complete, the pH of the solution was raised by addition of base to ca. 7.8.
U.S. Pat. No. 2,478,767 also describes a process for manufacturing lakes of azo compounds. The diazotizable amine is dissolved in an acidic, aqueous solution and heated to 100xc2x0 F. The coupling component and nitrosating reagent are dissolved in a basic, aqueous solution that is heated to 150xc2x0 F. The two solutions are mixed together controlling the pH of the mixture in the range of 6-7.2.
U.S. Pat. No. 2,478,768 also describes a process for manufacturing lakes of azo compounds. The process involves adding an acidic, aqueous solution containing a soluble salt of the laking agent to a basic, aqueous solution containing the diazotizable amine, coupling component and nitrosating reagent. The final pH of the reaction mass is 6-7.2.
U.S. Pat. No. 3,793,305 describes a one-step process for the preparation of azo dyes by simultaneously contacting and reacting a diazotizable amine, an active methylene coupling component and a diazotizing agent in an acidic, aqueous solution. The invention requires that the reaction media must be able to dissolve a portion of both the diazotizable amine and the coupling component. The active methylene coupling components named are: b-diketones, b-keto esters, b-keto amides, b-keto nitrites, anilides of cyanoacetic acid, heterocyclic b-keto amides and b-imino amides.
U.S. Pat. No. 4,035,350 describes a process for the preparation of azo dyes where the diazotizable amine and the coupling component are both in solution and the diazotizing agent is added. The invention requires that either the amine or coupling component contain an acid group. The invention also claims the use of polar aprotic solvents that are miscible with water.
Hashida, Y. et. al. reported in xe2x80x9cPhase Transfer-Catalyzed Azo Coupling Reaction in Two Phase Systemsxe2x80x9d, Bull. Chem. Soc. Jpn. 61, 905-909 (1988) the phase transfer catalyzed azo coupling reaction in a two phase system. This paper describes the coupling reaction between p-methoxybenzenediazonium tetrafluoroborate with N,N-dimethylaniline in a biphasic water-1,2-dichloroethane system with various phase transfer catalysts.
Tamagaki, S. et. al. reported in Chemistry Letters, pp. 1237-1240 (1982) for the Chemical Society of Japan that silica gel facilitated azo coupling reactions between p nitrobenzenediazonium tetrafluoroborate and aromatic amines. This process involves a solid-solid-liquid multiphase mixture via a solid-liquid interfacial azo-coupling reaction.
In March, J, xe2x80x9cAdvanced Organic Chemistry,xe2x80x9d Fourth Ed., New York, pages 522-523, it is pointed out that it is well known that active substrates such as phenols are readily nitrated under standard nitrosation conditions.
An object of the invention is to provide a facile and improved process for the preparation of 5-perfluoroalkyl substituted 2H-benzotriazole UV absorbers.
Another object of the invention is to provide a novel one-pot process for the preparation of 2-(2-nitrophenylazo)phenols, referred to in this application as monoazobenzene intermediates. These monoazobenzene intermediates are useful for the preparation of hydroxyphenyl benzotriazole UV absorbers.
The instant invention describes an improved process for the preparation of 5-perfluoroalkyl (for example trifluoromethyl) substituted 2H-benzotriazoles where in the diazotization step aqueous alkali metal (for instance sodium) nitrite and concentrated hydrochloric acid are replaced by aqueous alkali metal (for instance sodium) nitrite and concentrated sulfuric acid; and where aqueous alkali metal (sodium) nitrite and concentrated sulfuric acid are replaced with anhydrous nitrosylsulfuric acid with concentrated sulfuric acid as a diluent to allow operation at safe concentrations.
The instant invention more specifically pertains to a process for preparing a compound of formula (I) 
which process comprises
diazotizing a perfluoroalkyl substituted o-nitroaniline of formula (II) 
using concentrated sulfuric acid and an alkali metal nitrite (for instance sodium nitrite) or nitrosylsulfuric acid to form the corresponding diazonium salt of formula (III) 
coupling said diazonium salt with a phenol of formula (IV) 
to form a monoazobenzene compound of formula (V) 
reducing the monoazobenzene intermediate of formula (V) to the corresponding 2H-benzotriazole compound of formula (I) by conventional reduction means;
wherein
G1 is hydrogen or chloro,
G2 is perfluoroalkyl of 1 to 12 carbon atoms,
E1 is hydrogen, straight or branched chain alkyl of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 24 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms; or E1 is alkyl of 1 to 24 carbon atoms substituted by one or two hydroxy groups,
E2 is straight or branched alkyl chain of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms; or E2 is said alkyl of 1 to 24 carbon atoms or said alkenyl of 2 to 18 carbon atoms substituted by one or more xe2x80x94OH, xe2x80x94OCOE11, xe2x80x94OE4, xe2x80x94NCO, xe2x80x94NHCOE11, or xe2x80x94NE7E8, or mixtures thereof, where E4 is straight or branched chain alkyl of 1 to 24 carbon atoms; alkenyl of 2 to 18 carbon atoms; or said alkyl or said alkenyl interrupted by one or more xe2x80x94Oxe2x80x94, xe2x80x94NHxe2x80x94 or xe2x80x94NE4xe2x80x94 groups or mixtures thereof and which can be unsubstituted or substituted by one or more xe2x80x94OH, xe2x80x94OE4 or xe2x80x94NH2 groups or mixtures thereof; or E2 is xe2x80x94(CH2)mxe2x80x94COxe2x80x94E5;
E5 is OE or NE7E8, or
E5 is xe2x80x94PO(OE12)2, xe2x80x94OSi(E11)3 or xe2x80x94OCOxe2x80x94E11, or straight or branched chain C1-C24alkyl which can be interrupted by xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94NE11 and which can be unsubstituted or substituted by xe2x80x94OH or xe2x80x94OCOxe2x80x94E11, C5-C12cycloalkyl which is unsubstituted or substituted by xe2x80x94OH, straight chain or branched C2-C18alkenyl which is unsubstituted or substituted by xe2x80x94OH, C7-C15aralkyl, xe2x80x94CH2xe2x80x94CHOHxe2x80x94E13 or glycidyl,
E6 is hydrogen, straight or branched chain C1-C24alkyl which is unsubstituted or substituted by one or more OH, OE4 or NH2 groups, or xe2x80x94OE6 is xe2x80x94(OCH2CH2)wOH or xe2x80x94(OCH2CH2)wOE21 where w is 1 to 12 and E21 is alkyl of 1 to 12 carbon atoms,
E7 and E8 are independently hydrogen, alkyl of 1 to 18 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, straight or branched chain C3-C18alkyl which is interrupted by xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94NE11xe2x80x94, C5-C12cycloalkyl, C6-C14aryl or C1-C3hydroxylalkyl, or E7 and E8 together with the N atom are a pyrrolidine, piperidine, piperazine or morpholine ring, or
E5 is xe2x80x94Xxe2x80x94(Z)pxe2x80x94Yxe2x80x94E15 
wherein
X is xe2x80x94Oxe2x80x94 or xe2x80x94N(E16)xe2x80x94,
Y is xe2x80x94Oxe2x80x94 or xe2x80x94N(E17)xe2x80x94,
Z is C2-C12-alkylene, C4-C12-alkylene interrupted by one to three nitrogen atoms, oxygen atoms or a mixture thereof, or is C3-C12-alkylene, butenylene, butynylene, cyclohexylene or phenylene, each substituted by a hydroxyl group,
m is zero, 1 or 2,
p is 1, or p is also zero when X and Y are xe2x80x94N(E16)xe2x80x94 and xe2x80x94N(E17)xe2x80x94, respectively,
E15 is a group xe2x80x94COxe2x80x94C(E18)xe2x95x90C(H)E19 or, when Y is xe2x80x94N(E17)xe2x80x94, forms together with E17 a group xe2x80x94COxe2x80x94CHxe2x95x90CHxe2x80x94COxe2x80x94, wherein E18 is hydrogen or methyl, and E19 is hydrogen, methyl or xe2x80x94COxe2x80x94Xxe2x80x94E20, wherein E20 is hydrogen, C1-C12-alkyl or a group of the formula 
wherein the symbols E1, G2, X, Z, m and p have the meanings defined above, and E16 and E17 independently of one another are hydrogen, C1-C12-alkyl, C3-C12-alkyl interrupted by 1 to 3 oxygen atoms, or is cyclohexyl or C7-C15aralkyl, and E16 together with E17 in the case where Z is ethylene, also forms ethylene,
E11 is hydrogen, straight or branched chain C1-C18alkyl, C5-C12cycloalkyl, straight or branched chain C2-C18alkenyl, C6-C14aryl or C7-C15aralkyl,
E12 is straight or branched chain C1-C18alkyl, straight or branched chain C3-C18alkenyl, C5-C10cycloalkyl, C6-C16aryl or C7-C15aralkyl, and
E13 is H, straight chain or branched C1-C18alkyl which is substituted by xe2x80x94PO(OE12)2, phenyl which is unsubstituted or substituted by OH, C7-C15aralkyl or xe2x80x94CH2OE12,
with the proviso that when concentrated sulfuric acid and alkali metal nitrite are used, E1 and E2 are alkyl of 1 to 4 carbon atoms; or E1 can also be hydrogen.
In the above-described process, it is contemplated that the group G2 may also be phenyl, naphthyl, biphenylyl or 9-phenanthryl substituted by electron-withdrawing groups as described in co-pending application Ser. No. 09/722,876, filed Nov. 27, 2000. For example, G2 may be phenyl further substituted by perfluoroalkyl of 1 to 12 carbon atoms. The disclosure of application Ser. No. 09/722,876 is hereby incorporated by reference.
For example, the instant process involves the preparation of a compound of formula (Ia) 
which process comprises
diazotizing a substituted o-nitroaniline compound of formula (IIa) 
using concentrated sulfuric acid and sodium nitrite or nitrosylsulfuric acid to form the diazonium salt of formula (IIIa) 
coupling said diazonium salt with a phenol of formula (IVa) 
to form the corresponding monoazobenzene compound of formula (Va) 
reducing the monoazobenzene intermediate of formula (Va) to the corresponding 2H-benzotriazole compound of formula (Ia) by conventional reduction means;
with the proviso that when concentrated sulfuric acid and alkali metal nitrite are used, E1 and E2 are alkyl of 1 to 4 carbon atoms; or E1 can also be hydrogen.
For example, in the compound of formula (I),
G1 is hydrogen,
G2 is xe2x80x94CF3,
E1, is phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms,
E2 is straight or branched alkyl chain of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms; or E2 is said alkyl of 1 to 24 carbon atoms or said alkenyl of 2 to 18 carbon atoms substituted by one or more xe2x80x94OH, xe2x80x94OCOE11, xe2x80x94OE4, xe2x80x94NCO, xe2x80x94NH2, xe2x80x94NHCOE11, xe2x80x94NHE4 or xe2x80x94N(E4)2, or mixtures thereof, where E4 is straight or branched chain alkyl of 1 to 24 carbon atoms; or said alkyl or said alkenyl interrupted by one or more xe2x80x94Oxe2x80x94, xe2x80x94NHxe2x80x94 or xe2x80x94NE4xe2x80x94 groups or mixtures thereof and which can be unsubstituted or substituted by one or more xe2x80x94OH, xe2x80x94OE4 or xe2x80x94NH2 groups or mixtures thereof; or
is a compound of formula (I) wherein,
G1 is hydrogen,
G2 is xe2x80x94CF3,
E1 is hydrogen or straight or branched alkyl of 4 to 24 carbon atoms, and
E2 is as defined above.
For example, the compound of formula (I) is also where
G1 is hydrogen,
G2 is xe2x80x94CF3,
E1 is hydrogen, straight or branched alkyl of 4 to 24 carbon atoms or phenylalkyl of 7 to 15 carbon atoms,
E2 is (CH2)mxe2x80x94COxe2x80x94E5,
E5 is xe2x80x94OE6 or xe2x80x94NE7E8, or
E5 is xe2x80x94Xxe2x80x94(Z)pxe2x80x94Yxe2x80x94E15 
wherein
X is xe2x80x94Oxe2x80x94 or xe2x80x94N(E16)xe2x80x94,
Y is xe2x80x94Oxe2x80x94 or xe2x80x94N(E17)xe2x80x94,
Z is C2-C12-alkylene, C4-C12-alkylene interrupted by one to three nitrogen atoms, oxygen atoms or a mixture thereof, or is C3-C12-alkylene, butenylene, butynylene, cyclohexylene or phenylene, each substituted by a hydroxyl group,
m is 0, 1, 2 or 3,
p is 1, or p is also zero when X and Y are xe2x80x94N(E16)xe2x80x94 and xe2x80x94N(E17)xe2x80x94, respectively,
E15 is a group xe2x80x94COxe2x80x94C(E18)xe2x95x90C(H)E19 or, when Y is xe2x80x94N(E17)xe2x80x94, forms together with E17 a group xe2x80x94COxe2x80x94CHxe2x95x90CHxe2x80x94COxe2x80x94, wherein E18 is hydrogen or methyl, and E19 is hydrogen, methyl or xe2x80x94COxe2x80x94Xxe2x80x94E20, wherein E20 is hydrogen, C1-C12-alkyl or a group of the formula 
For instance, the compound of formula (I) is where
G1 is hydrogen,
G2 is xe2x80x94CF3,
E1, is phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms,
E2 is straight or branched alkyl chain of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms; or E2 is said alkyl of 1 to 24 carbon atoms or said alkenyl of 2 to 18 carbon atoms substituted by one or more xe2x80x94OH, xe2x80x94OCOE11, xe2x80x94NH2 or xe2x80x94NHCOE11, or mixtures thereof, or said alkyl or said alkenyl interrupted by one or more xe2x80x94Oxe2x80x94 and which can be unsubstituted or substituted by one or more xe2x80x94OH; or
is a compound of formula (I) wherein,
G1 is hydrogen,
G2 is xe2x80x94CF3,
E1 is hydrogen, straight or branched alkyl of 4 to 24 carbon atoms or phenylalkyl of 7 to 15 carbon atoms, and
E2 is as defined above.
For instance, the compound of formula (I) is where
G1 is hydrogen,
G2 is xe2x80x94CF3,
E1, is hydrogen, straight or branched alkyl of 4 to 24 carbon atoms or phenylalkyl of 7 to 15 carbon atoms,
E2 is xe2x80x94(CH2)mxe2x80x94COxe2x80x94E5,
E5 is xe2x80x94OE6 or xe2x80x94NE7E8 where
E6 is hydrogen, straight or branched chain C1-C24alkyl which is unsubstituted or substituted by one or more OH groups, or xe2x80x94OE6 is xe2x80x94(OCH2CH2)wOH or xe2x80x94(OCH2CH2)wOE21 where w is 1 to 12 and E21 is alkyl of 1 to 12 carbon atoms, and
E7 and E8 are independently hydrogen, alkyl of 1 to 18 carbon atoms, straight or branched chain C3-C18alkyl which is interrupted by xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94NE11xe2x80x94, C5-C12cycloalkyl, C6-C14aryl or C1-C3hydroxylalkyl, or E7 and E8 together with the N atom are a pyrrolidine, piperidine, piperazine or morpholine ring.
IIIustrative of the compounds of formula (I) which can be made by the instant process are
(a) 5-trifluoromethyl-2-(2-hydroxy-3-xcex1-cumyl-5-tert-octylphenyl)-2H-benzotriazole;
(b) 5-trifluoromethyl-2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole;
(c) 5-trifluoromethyl-2-(2-hydroxy-3,5-di-tert-octylphenyl)-2H-benzotriazole;
(d) 5-trifluoromethyl-2-[2-hydroxy-5-(2-hydroxyethyl)phenyl]-2H-benzotriazole;
(e) 5-trifluoromethyl-2-(2-hydroxy-3,5-di-xcex1-cumylphenyl)-2H-benzotriazole;
(f) 3-(5-trifluoromethyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamic acid;
(g) methyl 3-(5-trifluoromethyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamate;
(h) isooctyl 3-(5-trifluoromethyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamate;
(i) 5-trifluoromethyl-2-[2-hydroxy-5-(3-hydroxypropyl)phenyl]-2H-benzotriazole;
(j) 5-trifluoromethyl-2-[2-hydroxy-5-(3-acryloyloxypropyl)phenyl]-2H-benzotriazole;
(k) 5-trifluoromethyl-2-[2-hydroxy-5-(3-methacryloyloxypropyl)phenyl]-2H-benzotriazole;
(l) 5-trifluoromethyl-2-[2-hydroxy-5-(3-acrylylaminopropyl)phenyl]-2H-benzotriazole;
(m) 5-trifluoromethyl-2-[2-hydroxy-5-(3-methacrylylaminopropyl)phenyl]-2H-benzotriazole;
(n) 5-trifluoromethyl-2-(2-hydroxy-3-xcex1-cumyl-5-tert-butylphenyl)-2H-benzotriazole;
(o) 5-trifluoromethyl-2-(2-hydroxy-3-xcex1-cumyl-5-nonylphenyl)-2H-benzotriazole;
(p) 5-trifluoromethyl-2-[2-hydroxy-3-xcex1-cumyl-5-(2-hydroxyethyl)phenyl]-2H-benzotriazole;
(q) 5-trifluoromethyl-2-[2-hydroxy-3-xcex1-cumyl-5-(3-hydroxypropyl)phenyl]-2H-benzotriazole;
(r) 5-trifluoromethyl-2-(2-hydroxy-3,5-ditert-amylphenyl)-2H-benzotriazole;
(s) 5-trifluoromethyl-2-(2-hydroxy-3,5-ditert-butylphenyl)-2H-benzotriazole;
(t) 5-trifluoromethyl-2-(2-hydroxy-3-dodecyl-5-methylphenyl)-2H-benzotriazole;
(u) 5-trifluoromethyl-2-[2-hydroxy-3-tert-butyl-5-(3-hydroxypropyl)phenyl)-2H-benzotriazole; and
(v) 5-trifluoromethyl-2-[2-hydroxy-3-tert-butyl-5-(2-hydroxyethyl)phenyl]-2H-benzotriazole;
For example, the instant process involves the preparation of a compound of formula (Ib), 
which process comprises
diazotizing a substituted o-nitroaniline compound of formula (IIa) 
using nitrosylsulfuric acid to form the diazonium salt of formula (IIIa) 
coupling said diazonium salt with a phenol of formula (IVb) 
to form the corresponding monoazobenzene compound of formula (Vb) 
reducing the monoazobenzene intermediate of formula (Vb) to the corresponding 2H-benzotriazole compound of formula (Ib) by conventional reduction means.
For instance, the instant process involves the preparation of a compound of formula (Ic), 
which process comprises
diazotizing a substituted o-nitroaniline compound of formula (IIa) 
using nitrosylsulfuric acid to form the diazonium salt of formula (IIIa) 
coupling said diazonium salt with a phenol of formula (IVc) 
to form the corresponding monoazobenzene compound of formula (Vc) 
reducing the monoazobenzene intermediate of formula (Vc) to the corresponding 2H-benzotriazole compound of formula (Ic) by conventional reduction means. Ia. In the process for making the diazonium salts using a perfluoroalkyl substituted o-nitroaniline (i.e. 4-trifluoromethyl-2-nitroaniline, CF3-ONA), sulfuric acid and an aqueous alkali metal nitrite (i.e. sodium nitrite) solution, the following process parameters pertain:
a. The molar ratio of CF3-ONA:sulfuric acid is 1:10 to 1:1; for example 1:5 to 1:1; for instance 1:2-3.5.
b. The molar ratio of CF3-ONA:sodium nitrite is 1:1 to 1:4; for example 1:1 to 1:2; for instance 1:1.
c. The temperature used for this reaction is from xe2x88x9230xc2x0 C. to 50xc2x0 C.; for example from xe2x88x9220xc2x0 C. to 20xc2x0 C.; for instance from xe2x88x9210xc2x0 C. to 5xc2x0 C.
Ib. In the process for making the diazonium salts using a perfluoroalkyl substituted o-nitroaniline (i.e. 4-trifluoromethyl-2-nitroaniline, CF3-ONA) and nitrosylsulfuric acid in sulfuric acid, the following process parameters pertain:
a. The molar ratio of CF3-ONA:nitrosylsulfuric acid is 1:1 to 1:2; for example 1:1 to 1:1.2; for instance 1:1.
b. The molar ratio of CF3-ONA:sulfuric acid is 1:1 to 1:10; for example 1:2 to 1:7; for instance 1:2 to 1:5.
c. The temperature used for this reaction is from xe2x88x9230xc2x0 C. to 50xc2x0 C.; for example from xe2x88x9220xc2x0 C. to 40xc2x0 C.; for instance from 0xc2x0 C. to 25xc2x0 C.
When preparing a diazonium salt using nitrosylsulfuric acid, a very low amount of water is required. The system is essentially anhydrous. When sulfuric acid concentrations are under 90%, nitrosylsulfuric acid becomes nitric oxide (NO) and evolves as a gas before it has time to react with the CF3-ONA. At the end of the diazotization reaction, the diazonium salt solution in sulfuric acid is diluted with water to about 20-25%.
II. For the preparation of the monoazobenzene intermediate, there are two different coupling methods possible. The alkaline coupling method is described in detail in U.S. Pat. Nos. 4,275,004 and 4,347,180 which are incorporated herein by reference.
The acidic coupling process is described in detail in U.S. Pat. No. 5,436,322 which is incorporated herein by reference.
It is noted that instant Example 9 shows a coupling method which neither strongly alkaline nor strongly acidic. Rather, this Example shows coupling which is buffered with acetic acid and sodium hydroxide.
The details of the present specific acidic coupling method are described infra.
The diazonium salt formed as described above is reacted with the appropriate phenol in a solvent containing a surface active modifier at a temperature of xe2x88x9230xc2x0 C. to 75xc2x0 C.; for example at xe2x88x9220xc2x0 C. to 50xc2x0 C.; for instance at xe2x88x9210xc2x0 C. to 35xc2x0 C.
The solvents used are water, an aromatic hydrocarbon, an aliphatic hydrocarbon or a mixture thereof. For instance, the solvent is water, toluene, o-xylene, m-xylene, p-xylene or a mixture of said xylenes, mesitylene, pseudocumene, hexane, heptane, octane, nonane or a mixture thereof. For example, the solvent is water, toluene, o-xylene, m-xylene, p-xylene, a mixture of said xylenes, heptane or a mixture thereof.
The amount of solvent to be used is that sufficient to dissolve the reactants. The amount of solvent is not critical, but making the solution too dilute is to be avoided.
The surface active modifier to be used is any one or a mixture of materials selected from the group consisting of emulsifying agents, surfactants, phase transfer agents and dispersants.
For instance, the surface active modifier is HOSTAPUR(copyright) SAS93 (Hoechst) or PETROSUL(copyright) M-60 (Penreco). The amount used is that needed to ensure adequate mixing of the reactants.
The molar ratio of diazonium salt:phenol is 2:1 to 1:2; for example 1.5:1 to 1:1.5; for instance 1:1.
III. The monoazobenzene compounds prepared in the instant process can be conveniently reduced to the corresponding benzotriazolyl-1-oxide and then to the corresponding 2H-benzotriazole by any number of conventional reduction methods. An illustrative list of such methods is given below, but should not be construed as being the only methods possible for carrying out said reduction.
1. EP 0380840 A1 describes the hydrogenation of a benzotriazolyl-1-oxide to the benzotriazole using palladium/carbon catalyst in toluene/water and in the presence of dimethylamine.
2. EP 0380840 A1 also discloses the hydrogenation of a benzotriazolyl-1-oxide to the benzotriazole using Raney nickel catalyst in toluene/2-butanol and in the presence of 1,5-diazabicyclo[5.4.0]undecane.
3. EP 0380839 A1 discloses the hydrogenation of a nitromonoazobenzene to the benzotriazole using Raney nickel catalyst in toluene/isopropanol and in the presence of sodium hydroxide.
4. EP 0380839 A1 also discloses the hydrogenation of a nitromonoazobenzene to the benzotriazole using palladium/carbon catalyst in toluene/water/isopropanol and in the presence of dimethylamine.
5. Japanese Sho 37-5934 (1962) and U.S. Pat. No. 3,773,751 describe the reduction of a nitromonoazobenzene to the benzotriazole using zinc, sodium hydroxide in an alcohol.
6. U.S. Pat. No. 2,362,988 discloses a variety of methods for the reduction of a nitromonoazobenzene to a benzotriazole. These include the use of:
a. ammonium sulfide;
b. an alkali metal sulfide;
c. zinc and ammonia;
d. hydrogen sulfide and sodium; or
e. zinc and hydrochloric acid.
7. Japanese Sho 56-133076 (1981) describes the reduction of a nitromonoazobenzene to a benzotriazole using quinone plus a variety of coreactants. These include:
a. zinc;
b. ammonium sulfide;
c. alkali metal sulfide;
d. alkali metal hydrosulfide; or
e. hydrazine.
8. Japanese Sho 52-113973 (1977) and Sho 52-113974 (1977) describe the hydrogenation of a nitromonoazobenzene to a benzotriazole using a precious metal catalyst in the presence of a base.
9. Japanese Sho 59-170172 (1984) and Sho 63-72682 (1988) describe the reduction of a nitromonoazobenzene to a benzotriazole using a quinone or an aromatic ketone in the presence of an alcohol and a base and with heating.
10. Japanese Sho 61-215378 (1986) describes the reduction of a nitromonoazobenzene or a benzotriazolyl-1-oxide benzotriazole to a benzotriazole using an aldehyde and aromatic ketone in the presence of a base.
11. Japanese Sho 63-72683 (1988) and U.S. Pat. No. 4,780,541 describe the reduction of a nitromonoazobenzene or a benzotriazolyl-1-oxide benzotriazole to a benzotriazole using a primary or secondary alcohol and an aromatic ketone in the presence of a base.
12. Japanese Sho 63-186886 (1988) describes the electrolytic reduction of a nitromonoazobenzene or a benzotriazolyl-1-oxide benzotriazole to a benzotriazole using an alkali metal hydroxide in water or an aqueous alcohol solution.
13. Japanese Sho 61-215379 (1986) and U.S. Pat. No. 4,789,541 describe the reduction of a benzotriazolyl-1-oxide benzotriazole to a benzotriazole using an aldehyde and an aromatic ketone in the presence of a base.
14. U.S. Pat. No. 5,571,924 describes the reduction of a nitromonoazobenzene or a benzotriazolyl-1-oxide benzotriazole to a benzotriazole using hydrazine and a precious metal catalyst.
15. U.S. Pat. No. 3,978,074 discloses the reduction of a nitromonoazobenzene to a benzotriazole using a hydrogen and a noble metal catalyst in the presence of an aqueous alkali metal hydroxide solution.
16. U.S. Pat. No. 4,219,480 discloses the reduction of a nitromonoazobenzene to a benzotriazole using a hydrogen and a Raney nickel catalyst in the presence of an aqueous alkali metal hydroxide solution or in the presence of an aliphatic amine.
17. U.S. Pat. No. 4,230,867 discloses the reduction of a nitromonoazobenzene to a benzotriazole using a hydrogen and a noble metal catalyst in the presence of an aliphatic amine.
One-pot Process for the Preparation of 2-(2-Nitrophenylazo)phenols
The present invention also provides a facile and improved multiphase process for the preparation of 2-(2-nitrophenylazo) substituted phenols and corresponding benzotriazole UV absorbers. The instant one-pot process is a highly efficient and environmentally acceptable (xe2x80x9cGreen Chemistry: Theory and Practicexe2x80x9d by P. T. Anastas and J. C. Warner, Oxford press, 1998) in that: 1) The process can be carried out using environmentally friendly solvents (water, hydrocarbons, etc.); 2) The amount of corrosive, mineral acid required is low, decreasing waste handling issues and the formation of hazardous by-products; 3) It also offers safety advantages in that the diazonium salt is not isolated or processed in any way. The intermediate diazonium salt is generated in situ and reacted immediately, keeping diazonium concentrations to a minimum thereby minimizing the risk of explosion, worker exposure or release to the environment. For reagents containing fluorinated groups, the risk of generation and release of hazardous HF is eliminated; 4) The less stringent conditions produce fewer by-products resulting in higher yield and better product quality; 5) The process utilizes a single vessel eliminating the risk of transferring hazardous materials from one vessel to another; and 6) Cycle time is decreased resulting in better energy efficiency.
It is very surprising that the single vessel, simultaneous diazotization-coupling reaction works so well given that phenols are readily oxidized and nitrated under the same reaction conditions. See for example March, J, xe2x80x9cAdvanced Organic Chemistry,xe2x80x9d Fourth Ed., New York, pages 522-523.
Specifically, the instant one-pot process allows for the efficient preparation of a new class of benzotriazole ultraviolet light absorbers (UVA""s), that is benzotriazole UVA""s substituted in the 5 position of the benzo ring with a xe2x80x94CF3 group. Further, surprisingly, the present process may be applied to the preparation of 2-(2-nitrophenylazo) substituted phenol (monoazo) intermediates of previously known commercial benzotriazole UVA""s, that is benzotriazole UVA""s with weaker electron withdrawing groups in the benzo ring (such as chloro) or benzotriazole UVA""s with no electron withdrawing groups in the benzo ring. The environmental and safety benefits of the instant process are also realized in the preparation of these currently commercially available benzotriazoles.
Specifically, provided is a novel process for the preparation of 2-(2-nitrophenylazo) substituted phenols of the formula (VI) 
which process comprises combining an ortho-nitroaniline of formula (VII) 
a phenol of formula (VIII) 
a nitrosating agent
together in a multiphase reaction medium and reacting the mixture for a sufficient time without isolation of intermediate products,
wherein the multiphase medium comprises an organic and an aqueous phase and optionally a surface active agent;
wherein
G1 is hydrogen or chloro,
G2 is perfluoroalkyl (CnF2n+1) where n is equal to 1-12, hydrogen, halogen, NO2, cyano, R3Sxe2x80x94, R3SOxe2x80x94, R3SO2xe2x80x94, phenyl, naphthyl, biphenylyl, 9-phenanthryl or said phenyl, naphthyl, biphenylyl or 9-phenanthryl substituted by one to three alkyl of 1 to 18 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, R3Sxe2x80x94, R3SOxe2x80x94, R3SO2, aryl of 6 to 10 carbon atoms, perfluoroalkyl of 1 to 12 carbon atoms, halogen, nitro, cyano, carboxyl, alkoxycarbonyl of 2 to 19 carbon atoms, hydroxyl, alkoxy of 1 to 18 carbon atoms, aryloxy of 6 to 10 carbon atoms, aralkoxy of 7 to 15 carbon atoms, vinyl, acetyl, acetamido, amino, dialkylamino of 2 to 12 carbon atoms, formyl, thioalkoxy of 1 to 18 carbon atoms, hydroxymethyl, aminomethyl, halomethyl, sulfato, phosphato or where any two substituents form a benzo ring with the aryl moiety to which they are attached,
R1 is hydrogen, straight or branched chain alkyl of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 24 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms; or R1 is alkyl of 1 to 24 carbon atoms substituted by one or two hydroxy groups,
R2 is straight or branched alkyl chain of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms; or R2 is said alkyl of 1 to 24 carbon atoms or said alkenyl of 2 to 18 carbon atoms substituted by one or more xe2x80x94OH, xe2x80x94OCOE11, xe2x80x94OE4, xe2x80x94NCO, xe2x80x94NHCOE11 or xe2x80x94NE7E8, or mixtures thereof, where E4 is straight or branched chain alkyl of 1 to 24 carbon atoms; alkenyl of 2 to 18 carbon atoms; or said alkyl or said alkenyl interrupted by one or more xe2x80x94Oxe2x80x94, xe2x80x94NHxe2x80x94 or xe2x80x94NE4xe2x80x94 groups or mixtures thereof and which can be unsubstituted or substituted by one or more xe2x80x94OH, xe2x80x94OE4 or xe2x80x94NH2 groups or mixtures thereof; or R2 is xe2x80x94(CH2)mxe2x80x94COxe2x80x94E5;
R3 is alkyl of 1 to 20 carbon atoms, hydroxyalkyl of 2 to 20 carbon atoms, alkenyl of 3 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, aryl of 6 to 10 carbon atoms or said aryl substituted by one or two alkyl of 1 to 4 carbon atoms;
E5 is OE6 or NE7E8, or E5 is xe2x80x94PO(OE12)2, xe2x80x94OSi(E11)3 or xe2x80x94OCOxe2x80x94E11, or straight chain C1-C24alkyl which can be interrupted by xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94NE11 and which can be unsubstituted or substituted by xe2x80x94OH or xe2x80x94OCOxe2x80x94E11, C5-C12cycloalkyl which is unsubstituted or substituted by xe2x80x94OH, straight chain or branched C2-C18alkenyl which is unsubstituted or substituted by xe2x80x94OH, C7-C15aralkyl, xe2x80x94CH2-CHOHxe2x80x94E13 or glycidyl,
E6 is hydrogen, straight or branched chain C1-C24alkyl which is unsubstituted or substituted by one or more OH, OE4 or NH2 groups, or xe2x80x94OE6 is xe2x80x94(OCH2CH2)wOH or xe2x80x94(OCH2CH2)wOE21 where w is 1 to 12 and E21 is alkyl of 1 to 12 carbon atoms,
E7 and E8 are independently hydrogen, alkyl of 1 to 18 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, straight or branched chain C3-C18alkyl which is interrupted by xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94NE11xe2x80x94, C5-C12cycloalkyl, C6-C14aryl or C1-C3hydroxylalkyl, or E7 and E8 together with the N atom are a pyrrolidine, piperidine, piperazine or morpholine ring, or
E5 is xe2x80x94Xxe2x80x94(Z)pxe2x80x94Yxe2x80x94E15 
wherein
X is xe2x80x94Oxe2x80x94 or xe2x80x94N(E16)xe2x80x94,
Y is xe2x80x94Oxe2x80x94 or xe2x80x94N(E17)xe2x80x94,
Z is C2-C12-alkylene, C4-C12-alkylene interrupted by one to three nitrogen atoms, oxygen atoms or a mixture thereof, or is C3-C12-alkylene, butenylene, butynylene, cyclohexylene or phenylene, each substituted by a hydroxyl group,
m is zero, 1 or 2,
p is 1, or p is also zero when X and Y are xe2x80x94N(E16)xe2x80x94 and xe2x80x94N(E17)xe2x80x94, respectively,
E15 is a group xe2x80x94COxe2x80x94C(E18)xe2x95x90C(H)E19 or, when Y is xe2x80x94N(E17)xe2x80x94, forms together with E17 a group xe2x80x94COxe2x80x94CHxe2x95x90CHxe2x80x94COxe2x80x94, wherein E18 is hydrogen or methyl, and E19 is hydrogen, methyl or xe2x80x94COxe2x80x94Xxe2x80x94E20, wherein E20 is hydrogen, C1-C12-alkyl, and E16 and E17 independently of one another are hydrogen, C1-C12-alkyl, C3-C12-alkyl interrupted by 1 to 3 oxygen atoms, or is cyclohexyl or C7-C15aralkyl, and E16 together with E17 in the case where Z is ethylene, also forms ethylene,
E11 is hydrogen, straight or branched chain C1-C18alkyl, C5-C12cycloalkyl, straight or branched chain C2-C18alkenyl, C6-C14aryl or C7-C15aralkyl,
E12 is straight or branched chain C1-C18alkyl, straight or branched chain C3-C18alkenyl, C5-C10cycloalkyl, C6-C16aryl or C7-C15aralkyl, and
E13 is H, straight chain or branched C1-C18alkyl which is substituted by xe2x80x94PO(OE12)2, phenyl which is unsubstituted or substituted by OH, C7-C15aralkyl or xe2x80x94CH2OE12.
Halogen is for example chloro, fluoro or bromo.
For instance, provided is a process for the preparation of a compound of formula (VIa) 
which process comprises combining an ortho-nitroaniline compound of formula (VIIa) 
a phenol of formula (VIIIa) 
a nitrosating agent selected from concentrated sulfuric acid solution and sodium nitrite or nitrosylsulfuric acid,
together in a two phase reaction medium comprising an organic and an aqueous phase and a surface active agent and reacting the mixture for a sufficient time without isolation of intermediate products.
A particular embodiment of the invention produces a compound of formula (VI) or (VIa) wherein
G1 is hydrogen,
G2 is xe2x80x94CF3, halogen or hydrogen,
R1 is phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms,
R2 is straight or branched alkyl chain of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms; or E2 is said alkyl of 1 to 24 carbon atoms or said alkenyl of 2 to 18 carbon atoms substituted by one or more xe2x80x94OH, xe2x80x94OCOE11, xe2x80x94OE4, xe2x80x94NCO, xe2x80x94NH2, xe2x80x94NHCOE11, xe2x80x94NHE4 or xe2x80x94N(E4)2, or mixtures thereof, where E4 is straight or branched chain alkyl of 1 to 24 carbon atoms; or said alkyl or said alkenyl interrupted by one or more xe2x80x94Oxe2x80x94, xe2x80x94NHxe2x80x94 or xe2x80x94NE4xe2x80x94 groups or mixtures thereof and which can be unsubstituted or substituted by one or more xe2x80x94OH, xe2x80x94OE4 or xe2x80x94NH2 groups or mixtures thereof; and
R3 is hydrogen; or
a compound of formula (VI) or (VIa) wherein,
G1 is hydrogen,
G2 is xe2x80x94CF3, halogen or hydrogen,
R1 is hydrogen or straight or branched alkyl of 4 to 24 carbon atoms, and
R2 and R3 are as defined above.
In an alternative embodiment, the compound of formula (VI) or (VIa) is produced such that
G1 is hydrogen,
G2 is xe2x80x94CF3 or halogen,
R1 is hydrogen, straight or branched alkyl of 4 to 24 carbon atoms or phenylalkyl of 7 to 15 carbon atoms,
R2 is (CH2)mCOxe2x80x94E5,
R3 is hydrogen,
E5 is xe2x80x94OE6 or xe2x80x94NE7E8, or
E5 is xe2x80x94Xxe2x80x94(Z)pxe2x80x94Yxe2x80x94E15 
wherein
X is xe2x80x94Oxe2x80x94 or xe2x80x94N(E16)xe2x80x94,
Y is xe2x80x94Oxe2x80x94 or xe2x80x94N(E17)xe2x80x94,
Z is C2-C12-alkylene, C4-C12-alkylene interrupted by one to three nitrogen atoms, oxygen atoms or a mixture thereof, or is C3-C12-alkylene, butenylene, butynylene, cyclohexylene or phenylene, each substituted by a hydroxyl group,
m is 0, 1, 2 or 3,
p is 1, or p is also zero when X and Y are xe2x80x94N(E16)xe2x80x94 and xe2x80x94N(E17)xe2x80x94, respectively,
E15 is a group xe2x80x94COxe2x80x94C(E18)xe2x95x90C(H)E19 or, when Y is xe2x80x94N(E17)xe2x80x94, forms together with E17 a group xe2x80x94COxe2x80x94CHxe2x95x90CHxe2x80x94COxe2x80x94, wherein E18 is hydrogen or methyl, and E19 is hydrogen, methyl or xe2x80x94COxe2x80x94Xxe2x80x94E20, wherein E20 is hydrogen, C1-C12-alkyl.
In a still further embodiment, the compound of formula (VI) or (VIa) is where
G1 is hydrogen,
G2 is xe2x80x94CF3,
R1 is phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms,
R2 is straight or branched alkyl chain of 1 to 24 carbon atoms, straight or branched chain alkenyl of 2 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, phenylalkyl of 7 to 15 carbon atoms, phenyl, or said phenyl or said phenylalkyl substituted on the phenyl ring by one to three alkyl of 1 to 4 carbon atoms; or E2 is said alkyl of 1 to 24 carbon atoms or said alkenyl of 2 to 18 carbon atoms substituted by one or more xe2x80x94OH, xe2x80x94OCOE11, xe2x80x94NH2 or xe2x80x94NHCOE11, or mixtures thereof, or said alkyl or said alkenyl interrupted by one or more xe2x80x94Oxe2x80x94 and which can be unsubstituted or substituted by one or more xe2x80x94OH; R3 is hydrogen; or
is a compound of formula (VI) or (VIa) wherein,
G1 is hydrogen,
G2 is xe2x80x94CF3,
R1 is hydrogen, straight or branched alkyl of 4 to 24 carbon atoms or phenylalkyl of 7 to 15 carbon atoms, and
R2 and R3 are as defined above.
A further embodiment is the compound of formula (VI) or (VIa) where
G1 is hydrogen,
G2 is xe2x80x94CF3,
R1 is hydrogen, straight or branched alkyl of 4 to 24 carbon atoms or phenylalkyl of 7 to 15 carbon atoms,
R2 is xe2x80x94(CH2)mxe2x80x94COxe2x80x94E5,
R3 is hydrogen,
E5 is xe2x80x94OE6 or xe2x80x94NE7E8 where
E6 is hydrogen, straight or branched chain C1-C24alkyl which is unsubstituted or substituted by one or more OH groups, or xe2x80x94OE6 is xe2x80x94(OCH2CH2)wOH or xe2x80x94(OCH2CH2)wOE21 where w is 1 to 12 and E21 is alkyl of 1 to 12 carbon atoms, and
E7 and E8 are independently hydrogen, alkyl of 1 to 18 carbon atoms, straight or branched chain C3-C18alkyl which is interrupted by xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94NE11xe2x80x94, C5-C12cycloalkyl, C6-C14aryl or C1-C3hydroxylalkyl, or E7 and E8 together with the N atom are a pyrrolidine, piperidine, piperazine or morpholine ring.
Provided is a process for the preparation of a compound of formula (VIb) 
which process comprises combining an ortho-nitroaniline compound of formula (VIIb) 
a phenol of formula (VIIIb) 
nitrosylsulfuric acid in sulfuric acid
together in a two phase reaction medium comprising an organic and an aqueous phase and a surface active agent and reacting the mixture for a sufficient time without isolation of intermediate products;
wherein G2 is CF3, hydrogen, fluorine, chlorine or bromine.
In this case the nitrosating agent, nitrosylsulfuric acid in sulfuric acid, may be added as an aqueous or an acid solution.
Provided is a process for the preparation of a compound of formula (VIc) 
which process comprises combining an ortho-nitroaniline compound of formula (VIIc) 
a phenol of formula (VIIIc) 
nitrosylsulfuric acid in the form of an acid solution,
together in a two phase reaction medium comprising an organic and an aqueous phase and a surface active agent and reacting the mixture for a sufficient time without isolation of intermediate products.
As discussed supra, intermediate products in the present process for the preparation of compounds of formula (VI) are not isolated. Specifically, diazonium salt products of the ortho-nitroaniline are not isolated.
In the present process where the nitrosating agent is sulfuric acid and alkali metal nitrite (i.e. sodium nitrite), the following process parameters pertain:
a. The molar ratio of nitroaniline: sulfuric acid is 1:10 to 1:1; for example 1:5 to 1:1; and for instance 1:3.5.
b. The molar ratio of nitroaniline: sodium nitrite is 1:1 to 1:4; for example 1:1 to 1:2; for instance 1:1.
c. The temperature used for this reaction is from xe2x88x9230xc2x0 C. to 50xc2x0 C.; for example from xe2x88x9220xc2x0 C. to 20xc2x0 C.; for instance from xe2x88x9210xc2x0 C. to 5xc2x0 C.
Ib. In the process for the in situ generation of diazonium salts using a substituted ortho-nitroaniline and nitrosylsulfuric acid in sulfuric acid, the following process parameters pertain:
a. The molar ratio of nitroaniline: nitrosylsulfuric acid is 1:1 to 1:2; for example 1:1 to 1:1.2; for instance 1:1.
b. The molar ratio of nitroaniline: sulfuric acid is 1:1 to 1:10; for example 1:2 to 1:7; for instance 1:2 to 1:5.
c. The temperature used for this reaction is from xe2x88x9230xc2x0 C. to 50xc2x0 C.; for example from xe2x88x9220xc2x0 C. to 40xc2x0 C.; for instance from 0xc2x0 C. to 25xc2x0 C.
When the nitrosating agent is nitrosylsulfuric acid and sulfuric acid, the concentration of the solution is under 90% since nitrosylsulfuric acid can decompose to form nitric oxide (NOx) gases before it has time to react with the nitroaniline. A precharge of sulfuric acid may be used to limit the decomposition of nitrosulfuric acid and hence facilitate the diazotization reaction.
The present mixture is conveniently reacted at a temperature of xe2x88x9230xc2x0 C. to 75xc2x0 C.; for example at xe2x88x9220xc2x0 C. to 50xc2x0 C.; for instance at xe2x88x9210xc2x0 C. to 35xc2x0 C.
The organic solvents for use in the present multiphase process are selected from aromatic hydrocarbons, aliphatic hydrocarbons or mixtures thereof. Different solvents may be used for the dispersion and addition of phenolic compounds. For example, the organic solvent is ligroine, toluene, o-xylene, m-xylene, p-xylene or a mixture of said xylenes, mesitylene, pseudocumene, hexane, heptane, octane, nonane or a mixture thereof. For instance, the solvent is ligroine, toluene, o-xylene, m-xylene, p-xylene, a mixture of said xylenes, heptane or a mixture thereof. The amount of solvent is not critical, but making the solution too dilute is to be avoided. The essential attribute of the organic solvent is the ability to preferentially dissolve the phenolic compounds. The solvent must also be water immiscible as shown by phase separation when stirring is stopped.
The nitrosating agents are nitrosylsulfuric acid in an acid carrier or an aqueous alkali metal nitrite, such as sodium nitrite in an acidic environment. The nitrosating agent is for example a mixture of nitrosylsulfuric acid in sulfuric acid. Other appropriate acid carriers or acids include, without limitation, acetic acid, hydrochloric acid, fluoroboric acid. The ratio of organic solvent to water is for example 2:1 to 1:2. The acid is present in the reaction system prior to the addition of the nitrosating agent or added simultaneously therewith. The simultaneous addition can be done by separate addition or as a mixture (acid carrier). An acid carrier or acid environment is preferably present when preparing 2-(2-nitrophenylazo) substituted phenols from reagents characterized as electron deficient amines. Particular examples of electron deficient amines are trifluoromethyl, halogen and nitro-substituted aromatic amines, most especially when substituted by such groups in the 4-position of the benzene ring. Organic soluble buffers or bases increase the reactivity of the phenol toward the coupling reaction and limit the de-alkylation of the phenolic compound.
The surface active agent to be used is any one or a mixture of materials selected from the group consisting of emulsifying agents, surfactants, phase transfer agents and dispersants. For instance, the surface active modifier is at least one anionic surfactant. Suitable anionic surfactants include, for example, alcohol sulfates (e.g. alkali metal or ammonium salts of alcohol sulfates) and sulfonates, alcohol phosphates and phosphonates, alkyl sulfonates, alkylaryl sulfonates, alkali metal or ammonium salts of fatty acids, sulfonated amines, sulfonated amides, fatty sarcosinates such as sodium lauroyl sarcosinate, linear alkylated sulfonates such as alkylbenzene sulfonates where the R-group is attached between C6-C15, alcohol ether sulfates such as those with the structure Rxe2x95x90C8-C15 and where ethoxylation is between 1-7, secondary alkane sulfonates such as the Hostapur(copyright) SAS series supplied by Clariant, and mixtures thereof. A more complete list of anionic surfactants is provided in McCutcheon""s, Volume 1, Emulsifiers and Detergents, pp. 280-283 (1997), which is incorporated herein by reference. HOSTAPUR(copyright) SAS93 (Hoechst), which is a secondary alkane sulphonate sodium salt (paraffin sulphonate) or PETROSULS(copyright) M-60 (Penreco), which are petroleum sulphonate salts, are specific examples. The amount used is that needed to ensure adequate dispersion of the nitroaniline within the organic phase of the reaction system.
The molar ratio of nitroaniline:phenol may be for example 2:1 to 1:2; for example 1.5:1 to 1:1.5; for instance 1:1 to 1:0.85.
The 2-(2-nitrophenylazo) substituted phenol compounds of formula (VI) (monoazobenzene compounds) prepared by the instant process may be conveniently reduced to the corresponding benzotriazolyl-1-oxide and then to the corresponding 2H-benzotriazole by any number of conventional reduction methods. An illustrative list of such methods is given supra (references 1-17), and again should not be construed as being the only methods possible for carrying out said reduction.
IIIustrative of the corresponding benzotriazole compounds that can be made from the 2-(2-nitrophenylazo) substituted phenols prepared by the present process are:
(1) 5-trifluoromethyl-2-(2-hydroxy-3-xcex1-cumyl-5-tert-octylphenyl)-2H-benzotriazole;
(2) 5-trifluoromethyl-2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole;
(3) 5-trifluoromethyl-2-(2-hydroxy-3,5-di-tert-octylphenyl)-2H-benzotriazole;
(4) 5-trifluoromethyl-2-(2-hydroxy-5-(2-hydroxyethyl)phenyl)-2H-benzotriazole;
(5) 5-trifluoromethyl-2-(2-hydroxy-3,5-di-xcex1-cumylphenyl)-2H-benzotriazole;
(6) 3-(5-trifluoromethyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamic acid;
(7) methyl 3-(5-trifluoromethyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamate;
(8) isooctyl 3-(5-trifluoromethyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamate;
(9) 5-trifluoromethyl-2-[2-hydroxy-5-(3-hydroxypropyl)phenyl]-2H-benzotriazole;
(10) 5-trifluoromethyl-2-[2-hydroxy-5-(3-acryloyloxypropyl)phenyl]-2H-benzotriazole;
(11) 5-trifluoromethyl-2-[2-hydroxy-5-(3-methacryloyloxypropyl)phenyl]-2H-benzotriazole;
(12) 5-trifluoromethyl-2-[2-hydroxy-5-(3-acrylylaminopropyl)phenyl]-2H-benzotriazole;
(13) 5-trifluoromethyl-2-[2-hydroxy-5-(3-methacrylylaminopropyl)phenyl]-2H-benzotriazole;
(14) 5-trifluoromethyl-2-(2-hydroxy-3-xcex1-cumyl-5-tert-butylphenyl)-2H-benzotriazole;
(15) 5-trifluoromethyl-2-(2-hydroxy-3-xcex1-cumyl-5-nonylphenyl)-2H-benzotriazole;
(16) 5-trifluoromethyl-2-[2-hydroxy-3-xcex1-cumyl-5-(2-hydroxyethyl)phenyl]-2H-benzotriazole;
(17) 5-trifluoromethyl-2-[2-hydroxy-3-xcex1-cumyl-5-(3-hydroxypropyl)phenyl]-2H-benzotriazole;
(18) 5-trifluoromethyl-2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole;
(19) 5-trifluoromethyl-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
(20) 5-trifluoromethyl-2-(2-hydroxy-3-dodecyl-5-methylphenyl)-2H-benzotriazole;
(21) 5-trifluoromethyl-2-[2-hydroxy-3-tert-butyl-5-(3-hydroxypropyl)phenyl)-2H-benzotriazole;
(22) 5-trifluoromethyl-2-[2-hydroxy-3-tert-butyl-5-(2-hydroxyethyl)phenyl]-2H-benzotriazole;
(23) 5-fluoro-2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole;
(24) 5-chloro-2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole;
(25) 5-bromo-2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole;
(26) 5-chloro-2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole;
(27) 5-bromo-2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole;
(28) 5-chloro-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
(29) 2-(2-hydroxy-5-methylphenyl)-2H-benzotriazole;
(30) 5-fluoro-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
(31) 5-bromo-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
(32) 2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
(33) 5-chloro-2-(2-hydroxy-3,5-di-xcex1-cumylphenyl)-2H-benzotriazole;
(34) 5-fluoro-2-(2-hydroxy-3,5-di-xcex1-cumylphenyl)-2H-benzotriazole;
(35) 5-chloro-2-(2-hydroxy-3-xcex1-cumyl-5-tert-octylphenyl)-2H-benzotriazole;
(36) 5-bromo-2-(2-hydroxy-3-xcex1-cumyl-5-tert-octylphenyl)-2H-benzotriazole;
(37) 5-fluoro-2-(2-hydroxy-3-xcex1-cumyl-5-tert-octylphenyl)-2H-benzotriazole;
(38) 2-(2-hydroxy-3-xcex1-cumyl-5-tert-octylphenyl)-2H-benzotriazole;
(39) 5-chloro-2-(2-hydroxy-4-phenylphenyl)-2H-benzotriazole;
(40) 5-fluoro-2-(2-hydroxy-4-phenylphenyl)-2H-benzotriazole;
(41) 5-bromo-2-(2-hydroxy-4-phenylphenyl)-2H-benzotriazole;
(42) 2-(2-hydroxy-3,5-di-xcex1-cumylphenyl)-2H-benzotriazole;
(43) 5-chloro-2-[2-hydroxy-3-tert-butyl-5-(3-hydroxypropyl)phenyl]-2H-benzotriazole;
(44) 5-fluoro-2-[2-hydroxy-3-tert-butyl-5-(3-hydroxypropyl)phenyl]-2H-benzotriazole;
(45) 5-bromo-2-[2-hydroxy-3-tert-butyl-5-(3-hydroxypropyl)phenyl]-2H-benzotriazole;
(46) 2-[2-hydroxy-3-tert-butyl-5-(3-hydroxypropyl)phenyl]-2H-benzotriazole;
(47) 3-(5-chloro-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamic acid;
(48) 3-(5-bromo-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamic acid;
(49) 3-(5-fluoro-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamic acid;
(50) 3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamic acid;
(51) 3-(5-chloro-2H-benzotriazol-2-yl)-5-xcex1-cumyl-4-hydroxyhydrocinnamic acid;
(52) 3-(5-bromo-2H-benzotriazol-2-yl)-5-xcex1-cumyl-4-hydroxyhydrocinnamic acid;
(53) 3-(5-fluoro-2H-benzotriazol-2-yl)-5-xcex1-cumyl-4-hydroxyhydrocinnamic acid;
(54) methyl 3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamate;
(55) methyl 3-(5-chloro-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamate;
(56) methyl 3-(5-chloro-2H-benzotriazol-2-yl)-5-xcex1-cumyl-4-hydroxyhydrocinnamate;
(57) 5-chloro-2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole;
(58) 5-fluoro-2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole;
(59) 5-bromo-2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole;
(60) 2-(2-hydroxy-3,5-di-tert-amylphenyl)-2H-benzotriazole;
(61) 5-phenylsulfonyl-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
(62) 5-octylsulfonyl-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
(63) 5-phenylsulfonyl-2-(2-hydroxy-3,5-di-xcex1-cumylphenyl)-2H-benzotriazole;
(64) 5-phenylsulfonyl-2-(2-hydroxy-3,5-di-xcex1-cumylphenyl)-2H-benzotriazole;
(65) 5-phenylsulfonyl-2-(2-hydroxy-3-xcex1-cumyl-5-tert-octylphenyl)-2H-benzotriazole;
(66) 5-octylsulfonyl-2-(2-hydroxy-3-xcex1-cumyl-5-tert-octylphenyl)-2H-benzotriazole;
(67) 5-butylsulfonyl-2-(2-hydroxy-3-xcex1-cumyl-5-tert-octylphenyl)-2H-benzotriazole;
(68) 5-ethylsulfonyl-2-(2-hydroxy-3-xcex1-cumyl-5-tert-octylphenyl)-2H-benzotriazole;
(69) 5-n-dodecylsulfonyl-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole;
(70) 5,5xe2x80x2-sulfonyl-bis[2-(2-hydroxy-3-xcex1-cumyl-5-tert-octylphenyl)-2H-benzotriazole];
(71) octyl 3-(5-phenylsulfonyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamate;
(72) 3-(5-phenylsulfonyl-2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamide; or
(73) 5-phenylsulfonyl-2-[2-hydroxy-3-tert-butyl-5-(3-hydroxypropyl)phenyl]-2H-benzotriazole;
(74) 2-(2-hydroxy-3,5-di-tert-octylphenyl)-2H-benzotriazole;
(75) 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole;
(76) isooctyl 3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyhydrocinnamate; and
(77) 2-(3-t-butyl-2-hydroxy-5-(2-(xcfx89-hydroxy-octa-(ethyleneoxy)carbonyl-ethyl)-, phenyl)-2H-benzotriazole, Tinuvin(copyright) 1130.